Most reliable for me is a tie between my Gen4 G26 and my XDm 4.5" 9mm. The XDm especially as it has had tens of thousands of rounds through it (G26 only has about 2k) and has never once malfunctioned. I would love to add my Gen4 G17 and make it a 3 way tie but the first few hundred rounds were troublesome (usual FTE/FTF issues the Gen4 has on occasion). Thousand of rounds later it is very reliable and does not malfunction. It still spits brass at me from time to time though. =(